The tag
property will tell you which view has been tapped. Set the proper tag when you create your view and in your action method that's been triggered on tap you can call a delegate method that will notify your delegate about which view has been tapped. Make your viewcontroller has the delegate and it will received the notification.
// your target method will look like this:
- (void) didTap:(id)sender {
//... your code that handle flipping the card
[self.delegate didTapOnCard:self]; // where delegate is your view controller
}